Electric valve starting system



Dec. 21, 1937. M. HURLIMANN ELECTRIC VALVE STARTING SYSTEM Filed July 5, 1936 Patented Dec. 21, 1937 'res - Unirse s warst- ELECTRIC VALVE STARTING SYSTEM Max Hiirlirnann, Baden, Switzerland, assignor to Aktiengesellschaft Brown Boveri &' Cie, Baden, Switzerland, a joint-stock company of Switzerland Application July a, 1936, serial No. 88,719 eoiaims. (Cl. 17e- 363) This invention relates in general to electric valve starting systems, and more particularly to a system for causing the continued operation of an ignition mechanism of the liquid jet type for .5; a valve of the liquid cathode type and for causing such operation to cease upon establishment of a flow of exciting current through the valve.

Electric valves of the liquid cathode type may advantageously` be provided with a so-called igniting mechanism whereby a solenoid causes some of the cathode material to be projected momentarily as a jet against an ignition anode connected with a source of direct current, whereby an arc is struck between the ignition anode 15, and the cathode upon breaking of the jet. It is,

however, usually more convenient to avoid the use of such source oi direct current and instead of such direct current, to supply alternating current or pulsating rectified current to the ignition 2o anode. The moment of interruption of the jet may then occur when the voltage present between the ignition anode and the cathode is not suiicient to cause an arc to be established therebetween, or even when such voltage is of the wrong polarity. Under such circumstances it is 'necessary to continually impress current impulses on the solenoid to produce a series of jets between the cathode and the ignition anode,

until a jet is broken while the voltage between the ignition anode and .the cathode is of the proper magnitude and polarity, and to cause the operation of the solenoid to cease when a llow of excitation current is established through the valve. Such results are preferably obtained automatically by means of a relay having the coil thereof connected in parallel with the solenoid and oi a second relay having the coil thereof connected in the excitation circuit of the valve.

The proper operation of the system also requires that the output circuit of the valve be maintained open during operation of the starting system.

It is, therefore, one of the objects of the present invention to provide a starting system for an electric valve of the liquidcathode type, in

which system jets of cathode material are continually produced between the cathode and an ignition anode.

`Another object of the present inventionis to provide a starting system of the liquid jet type for an electric valve having a liquid cathode,

which ceases to function when a flow of lexcitation current is established through the valve.

Another object of the present invention is to provide a starting system for an electric valve of the liquid cathode t-ype which may operate only when the valve is disconnected from the output circuit thereof.

Objects and advantages other than those above described will be apparent from the following description when read in connection with the ac- 5 companying drawing, in which:

Fig. 1 diagrammatically illustrates an embodiment of the present invention in which the ignition anode of the Valve receives a ow of alternating current; f 10 Fig. 2 is a cross sectional view through the ignition mechanism of the valve illustrated in Fig. l; and

Fig. 3 diagrammatically illustrates the modications to be brought to the embodiment illusl5 trated in Fig. l for supplying rectied current to the ignition anode of the valve. y

Referring more particularly to the drawing by characters of reference, reference numeral 4 generally designates an electric valve having a 20 casing 5 enclosing a liquid cathode t lying in a well 'l of the casing and a plurality of main anodes 3, but it will be understood that the present system is also applicable to the control of valves having a single main anode. Valve 4 may 25 be utilized for any desired purpose but, inthe present application, will be assumed to be ernployed as part of an alternatingcurrent rectifying system. Anodes 8 are accordingly connected with an alternating current supply cir- '30 cuit 9 through a transformer Il, the transformer being connected with one conductor cf a direct current output circuit l2 having the second conductor thereof connected with cathode t through a circuit breaker I3. Valve t is provided with a 35 plurality of excitation anodes M, anodes 3 and I4 all extending through the casing 5 of the valve in insulated relation therewith. The valve is also provided with an ignition anode i6 adjacent the surface of cathode 6 and which may be in- 0 sulated from the casing of the valve, but which may also be conductively connected therewith or may even constitute a part of the casing, which is generally insulated from the cathode.

The ignition mechanism of the valve is illus- 45 trated in detail in Fig. 2, and comprises a solenoid I1 arranged about an extension I8 of well l. The extension is made of magnetic material and constitutes the xed core of the solenoid. The solenoid is preferably supported by a cup shaped 50 shield i9 bolted on extension i8 and cooperating with a washer 2l in closing the magnetic circuit of the solenoid. Extension i8 is hollowed to dene a cylinder adapted to receive the movable armature 22 of the solenoid. The armature 55 Ving of non-magnetic material to prevent excessive magnetic attraction between the armature Vand the walls of the cylinder, which would result in excessive side thrust therebetween. Such coating may consist of a non-magnetic metal,-

`nozzle directed toward ignition anode I6, and

adapted to produce a jet of cathode material extending through cathode 3 and between the cathode and the ignition anode upon downward movement of the armature, from the rest position thereof shown, resulting from energization of solenoid I'I. As a portion 'of the magnetic flux produced by the solenoid flows through the portion of the wall of the cylinderV extending within the solenoid, such portion is preierably made as thin as is practically feasible.

The source of current for solenoid I'l and for anodes I4 and I6 may be any alternating current circuit such as circuit S, the connection l:therebetween comprising a switch 24 and a transformer 23 having a primary winding 21 and having a secondary winding 28 provided with a plurality of terminals and with a midt'ap. Although transformer 23 is herein represented as a single-phase transformer, a polyphase transformer would be used if excitation anodes I4 were greater in number than two. The excitation anodes are connected with the terminals of winding 28 through current limiting resistors 29, and ignition anode Iii is connected with one of such terminals through Va current-l limiting resistor 3I and throughY contacts 32 of a relay 33. Another relay 34 has the coil thereof connected in parallel withy solenoid I'I and is provided with` contacts 33 connecting the solenoid and the coil of relay 34 between two terminals of windingv 28 through contacts 31 of* relay 33. Relay 34 may be an inherently slow acting relay, or may be provided with4 suitable time delay means 33 operable to retard the closure of contacts 33. Relay 33 is provided with contacts 3S to complete a circuit for a signal device, such as a glow lamp 39, with secondary winding 2,8 upon operation of the relay. Cathode 6 is connected with the midtap of secondary winding 28 through a holding coil 4I for the latch 42 of circuit breaker I3, through the coil of relay 33, and through a reactor 43.

The operation of the system is initiated by closure of switch 24, whereby transformer 26 is energized from circuit 9. Current then flows from winding 2,8 through solenoid IT and the coil of relay 34, through contacts 36 and through contacts 31 back to winding 23. Solenoid il accordingly -attracts armature 22, thus causing a jet of cathode material to be produced between cathode Q and ignition anode I6, relay 34 at the same time attracting the armature thereof to open contacts 36. Solenoid I7 and the coil of relay 34 are thus operatively disconnected from winding 28, and armature 22 and relay 34 return to the position shown. The relay is so designed that armature 22 returns to the rest position` thereof before reclosure of contacts 3B, such result being preferably obtained by the provision of time delay means 35 on the relay. Upon the closure of contacts 33, solenoid I'I and the coil of relay 34 are reenergized and the above sequence of operation is repeated as Ylong as contacts 31 remain closed. Solenoid I'l is thus caused to continually receive current impulses from winding 23, and the resulting reciprocating movement of armature 22 causes jets of cathode material to be continually projected and broken between cathode 6 and ignition anode IE. Each time such arjet is projected, current flows from winding 2.8 through resistor 3l, ignition anode I6, cathode I, coil 4I, the coil of relay 33 and reactor 43 back to winding 23, such current being, however, insufcient in magnitude to'cause operation of Vlatch Y42 or of relay 33. Such current is interrupted each time armamature 22 reaches the fully attracted position thereof, the jet of cathode material produced by movement of the armature then being interrupted. A number of suchV successive interruptions may occur at instants atiwhich ignition anode IB is at a negative potential with respect to the potential of cathode 6, or is at a positive potential insufcient to causean arc to be established between the ignition anode and the cathode.

After a few operations of solenoid I'I, or sometimes even after the rst operation thereof, the jet is broken when anode I5 is at a positive potential, with respect to the potential of cathode 6, such that an arc is drawn therebetween, such arc being characterized by the establishment of a so-called cathode spot at which cathode 6 emits electrons for the ow of current between any of the anodes of valve 4 and the cathode through the space conned within the valve. Upon establishment of-su'ch cathode spot, another arc is established between excitation anodes i4 Vand the cathode, and current ows from Vwinding 28 through the resistors 29, excitation anodes I4, cathode 6, coil 4I, the coil of relay 33 and reactor 43 back to winding 23. Such current is a rectified current, which is maintainedY continuous and substantially uniform by the action of reactor 43, although the Vvoltage under which such current iiows is a pulsating voltage decreasing to zero twice during each cycle of the voltage circuit 3. Such current is of sufficient magnitude as to cause relay 33 to operate in response thereto, to thereby operatively disconnect ignition anode i5 and solenoid II from@ winding 28, thus preventing any further operation of the ignition system. Relay 33 closes contacts-38, thus energizing lamp 39 which gives an indication that the starting operation of the valve is completed. Circuit breaker I3 may then be closed, and Vis maintained closed by latch 42, which is maintained in latching position by coil 4I'.

If the excitation current of valve 4 is interrupted for any reason, latch 42 is released by coil 4I and thus causes opening of circuit breaker I3. Relay 33 returns to the position shown, andthe Valve is started again in the manner above described provided that transformer 23 is energized. It is necessary to cause circuit breaker I3 to open before solenoid VI begins to function, for the reason that ii circuit breaker I3 remained closed and if an arc were struck between cathode 3 and ignition anode I6 while the ignition anode was at a negative potential with respect to the potential of Ythe cathode, current could iiow from transformer II through Yanodes 8, through ignition anode` IIi'thenfunctioning as a cathode, through resistor 3l, contacts 32, winding 28,'reactor 43, the coil of relay 33, coil 42 and line l2 back to transformer I l. The secondary voltage of transformer Il being generally much higher than the voltage of winding 2.8,k such current would be greater than the maximum current for which the ignition and excitation circuits are designed, and such circuits would be seriously damaged.

In the embodiment partially illustrated in Fig. 3 resistor 3| is connected with one terminal of winding 28 through contacts 32 of relay 33 and through one of a pair of rectifying devices 44, the resistor being also connected with the other terminal of winding 28 through additional contacts 46 of relay 33 and through'the other device 44. In such manner, the flow of current between ignition anode IG and cathode 6 during connection therebetween through a jet is unidirectional, and an arc may be established at the cathode during either half cyc-le of` the voltage of supply circuit 9. However, it is again necessary to provide I for repeated operation of solenoid l1, as a jet established between cathode 6 and ignition anode I6 may be broken while the ignition anode is at substantailly cathode potential, so that an arc would not be established between the ignition anode and the cathode until after another operation of the solenoid. Once such arc is established, the flow of current through ignition anode I6 is maintained continuous and substantially uniform by the action of reactor 43, so that the cathode spot of cathode 6 is maintained even if the flow of current through excitation anodes I4 establishes itself several cycles after the establishment of the arc between the ignition anode and the cathode.

Although but two embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various modifications and changes may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In combination, an electric valve comprising a casing enclosing a liquid cathode and an ignition anode, a solenoid having an armature adapted upon attraction thereof by said solenoid from a rest position to cause a jet of cathode material to be projected from said cathode to said ignition anode, a source of current connected with said solenoid, and a relay having a coil connected in parallel with said solenoid and having contacts controlling therethrough the supply of current from said source to said solenoid and said .relay coil whereby the supply of said current to said solenoid and relay coil is simultaneously interrupted and the said solenoid is caused to continually receive current impulses from said source.

2. In combination, an electric valve comprising a casing enclosing a liquid cathode and an ignition anode, a solenoid having an armature adapted upon attraction thereof by said solenoid from a rest position to cause a jet of cathode material to be projected from said cathode to said ignition anode, a source of current connected with said solenoid, a relay having a coil connected in parallel with said solenoid and having contacts opening upon operation of said relay to operatively disconnect said source from said solenoid and from said relay coil, and means for delaying reclosure of said relay contacts until 'after return of said solenoid armature to the rest position.

3. In combination", an electric valve comprising a casing enclosing a liquid cathode and an ignition anode, asolenoid having an armature adapted upon repeated attraction thereof by said solenoid from a rest position to cause a succession of jets of cathode material to be projected from said cathode to said ignition anode, a source of current connected with said solenoid, a relay having a coil connected in parallel with said solenoid and having. contacts controlling therethrough the supply of current from said source to said solenoid and said relay coil whereby the supply of said current to said solenoid and relay coil is simultaneously interrupted and the said solenoid is caused to continually receive current impulses from said source, and means for connecting said source with said ignition anode and said cathode to cause an arc to be established therebetween upon interruption of one of said jets of cathode material.

4. In combination, an electric valve comprising a casing enclosing a liquid cathode, an ignition anode and a plurality of excitation anodes, a solenoid arranged outside of said casing and having an armature immersed in said cathode and adapted to produce a jet of cathode material between said cathode and said ignition anode upon energization of said solenoid, an alternating current supply circuit, a transformer having a primary winding connected with said supply circuit and having a secondary winding provided with terminals and with a midtap, means for connecting said excitation anodes with said transformer terminals, means for connecting said ignition anode with one of said transformer terminals, a relay having a coil connected in parallel with said solenoid and having contacts connecting said solenoid and said relay coil between two of said transformer terminals whereby said sole' noid is caused to continually receive current impulses from said transformer, and a second relay having a coil connecting said cathode with said transformer midtap and operable in response to the flow of excitation current therebetween to disconnect said ignition anode and said solenoid from said transformer.

5. In combination, an electric valve comprising a casing enclosing a liquid cathode, a plurality of main anodes and of excitation anodes, and an ignition anode, a solenoid having an armature immersed in said cathode and adapted to produce a jet of cathode material between said cathode and said ignition anode upon energization of said solenoid,V an alternating current supply circuit, a direct current load circuit connected with said supply circuit, a circuit breaker connecting said load circuit with said cathode, a transformer having a primary Winding connected with said supply circuit and having a secondary winding provided with terminals and with a midtap, means for connecting said excitation anodes with said transformer terminals, means for connecting said ignition anode with one of said transformer terminals; a relay having a coil connected in parallel with said solenoid and having contacts connecting said solenoid and said relay coil between two of said transformer terminals, whereby said solenoid is caused to continually receive current impulses from said transformer, a second relay having a coil connecting said cathode with said transformer midtap and operable in response to the flow of excitation current therebetween to disconnect said ignition anode and said solenoid from said transformer, and means for causing opening of said circuit breaker upon interruption of'sraid excitation current. l Y

6. In combination, an electric Valvecomprising a casing enclosing Aa liquid cathode, an ignition anode and a plurality of excitation anodes, a solenoid arranged outside of said casi-ng having an armature immersed in saidv cathode and adapted to produce a jet of cathode material between said cathode and said ignition anode upon energization of said solenoid, an alternating Vcurrent supply circuit, a transformer having a primary winding connected with said supply circuit and having a secondary winding pro-vided with terminals and with a midtap, means for connecting said excitation anodes Withsaid transmidtap and operable in response to the flow of excitation current therebetween to disconnect said ignition anode Vand said solenoid from said transformer. Y

MAX HURLIMAN'N. 

